Field of the Invention
The present invention generally relates to an information recording/reproducing apparatus, and more particularly to an information recording/reproducing apparatus for recording/reproducing data on an optical disc having a track structure having a storage area composed of a plurality of sectors.
Conventional information recording/reproducing devices include an information recording/reproducing apparatus of the read-only type in which information of a read-only information storage medium is reproduced and another information recording/reproducing apparatus of the recording/reproducing type in which information is recorded onto and reproduced from a medium capable of recording/reproducing information.
In the conventional information recording/ reproducing apparatus of the read-only type, a read-only optical disc (hereinafter referred to as "R/O disc") in which data have been recorded in the form of uneven pit portions on a disc-like plastic substrate is irradiated with a laser beam to thereby reproduce the data. In this apparatus, there is provided no recording means and data which have been recorded on a R/O disc by means of any other means are reproduced. Because of a large capacity, random accessibility, easiness in large quantity reproduction, and a low cost, the R/O disc has been proposed to use as a disc for recording a dictionary for word processing and/or font patterns, or as a disc for storing programs, manuals, etc.
In the conventional information recording/ reproducing apparatus of the recording/reproducing type, on the other hand, data recording as well as data reproducing can be carried out on a writable optical disc (hereinafter referred to as "writable disc") by irradiating the writable disc with a laser beam and there are provided recording means as well as reproducing means. The writable disc not only has properties of a large capacity and random accessibility similarly to the R/O disc, but is capable of performing data recording which is impossible on the R/O disc, and therefore utilization of the R/O disc has been proposed as an auxiliary storage for a computer like a hard disc and a floppy disc.
However, since a R/O disc is used only for reading data and produced in an exclusive factory, it is impossible for a user to change or supplement various data supplied by the R/O disc. Data subject to a computer are, however, frequently changed, so that it is necessary for a user to buy a new R/O disc every time the data are changed and it is required for a supplier to produce a new R/O disc every time the data are changed. Thus, there has been a problem that a R/O disc has a limit in use particularly when used in a computer because it can deal with only fixed and stationary data.
On the other hand, a writable disc has a problem that plenty of time is required when a larger quantity of information storage media of the same contents are duplicated, while there has been not such a problem that data recording cannot be achieved like the foregoing R/O disc.